Drag Suspension Setup??

[Zian Racing]

Hey guys we are curently redesigning the suspension for our r33gtr drag car. A little info its fully gutted rb26 twin turbo dynos @825 bhp we currently have hks drag suspension on and would like some opinions on setups the boys at the shop say hard springs all round BUT i say drop the coils low in the rear with stage 4 on the shock (1=soft 5=hard) in the front 3/4 low and 3 on the shock. mind you this thing so far is real touchy to keep straight if you launch wrong. all the videos i see from japanese twin turbo drag skylines the @$$ slams to the floor on the launch but have great 60 ft times high grip we are on hoosiers full slick 4 wheel drive. any suggestions would be appreciated

[2rismo]

Nice and soft in the front with as little rebound damping as possible (not sure if HKS drag dampers are rebound adjustable though) and pretty stiff in the back. You don't want to launch insanely hard but only have the inside 4" of slick on the ground at the back.

IRS cars ruin camber settings chronically on big launches and tend to walk all over the place if they're too soft at the back.

Good luck.

Adrian

[NXTIME]

Any more info and pics on your car and engine specs? Best 1/4 mile time and ET?

[skyline]

To ALL,

I dont profess to much about susp setups for gtr's,however the best way to get a gts-t off the line is to run std springs and ride height,use std rear shocks and have your front shocks converted by peders to 90/10's.This set gets the nose in the air and makes the arse squat fairly hard.I witnessed Kier Wilson's 8.8 sec run in his gtr and it had the front wheels off the ground it was an exceptional run!

Regards,

SKYLINE(Kym)...

[2rismo]

the best way to get a gts-t off the line is to run std springs and ride height,use std rear shocks and have your front shocks converted by peders to 90/10's.

The fastest GTS-t's run this setup do they?

Adrian

[Sydneykid]

If you haven't already done it, you need to fix the rear suspension alignment so you can run soft in the rear without excessive camber change. Nothing fundamently wrong with the HKS drag suspension but you need to tune it (including springs rates) for your tracks. The really fast tracks in Japan are very smooth, so they tend to run higher sprng rates than we do on our rougher tracks. Rear spring rate is very critical, you want a fair bit of weight transfer to the rear, even though it is 4wd. It is important to have adjustable ATTESSA (torque split) then you can optimise the balance of rear squat, traction and power to achieve the fastest 60'.

Bottom line, there is no one RIGHT setting, you have to optimise every day. So it is important to test the range of settings at your disposal, that way you will know what works and what doesn't. As for shocks, I suggest starting off with the lowest bump setting you can get on the rear and the lowest rebound setting on the front. You want to hold the back down until you can feed in some front torque without loosing steering. So a middle setting on the rear rebound would be where I would start. The front bump is adjusted so that when the weight does come back onto the front you don't get a bounce back that the soft rebound can not control.

I suggest testing the 60' techniques until you are happy, then half track passes. When you have them down pat, try a full track pass. You don't have to do wear the car out doing full track passes to tune the launches. If you don't already have it, I strongly suggest some data logging as that will lead you to the right answers faster than any other method. At the very least take videos of every run, side on mostly, some rear. Watch them in slomo carefully, it will show you what the car is doing.

Hope that helps

[the phantom]

how do you 'fix' the rear alignment to minimise camber change??

[Sydneykid]

how do you 'fix' the rear alignment to minimise camber change??

Ahhh Mr Walker, how the devil are you? :wassup: (for you non Phantom readers, Devil was the Ghost Who Walk's dog)

You can change the dynamic camber by moving the control arm mounting points. For example, by lowering the upper outer pivot point (or rasing the inner upper pivot point) you will get less negative camber on suspension compression. This can be achieved by eccentric bushes. You can also do the lower arm inner, but they are usually longer and thus the eccentric buhese have a smaller (but still valuable) effect.

Hope that helps

[NXTIME]

Excellent and helpful information, as usual, SK.

[Luffy]

Ive got a drag prepared R32 GTST and the suspension setup is hard and low at front, softer and higher at back!

[NXTIME]

My R32 suspension was set up like that from Japan. I haven't gotten round to looking at it any closer yet.